A self-stiffened panel consists mainly of a flat or curved outer skin to which stiffeners perpendicular to the plane of the panel are attached so as to improve the resistance of this sheet with respect to mechanical stresses that are applied thereto.
Each stiffener is an elongate element the vertical cross section of which is L-shaped, T-shaped or U-shaped. The stiffener thus comprises a horizontal portion which is parallel and is fixed to the outer skin, and one or more vertical longitudinal portions which are perpendicular to the main plane of the outer skin.
According to one known embodiment, the outer skin and the stiffeners are made of a composite material; they comprise fibers of at least one material, referred to as reinforcing fibers, which are joined together by a matrix such as a resin.
A conventional method for producing such a self-stiffened panel consists in positioning the outer skin on a molding support, then in fitting the skins intended to form the stiffeners preformed on the outer skin. The assembly is covered by a vacuum bag for forming an air gap around the skins.
Next, wedging means are disposed above the vacuum bag in order to keep the vertical portions of the stiffeners in position. The assembly is placed in an oven in order to polymerize the resin. While they are being fitted, the outer skin and the skins intended to form the stiffeners are preimpregnated with resin. The skins intended to form the stiffeners are fitted by way of preforms, or inserts, which are then withdrawn before the air pocket is put in place, followed by the wedging means.
Before the wedging means are put in place, the vertical portions of the stiffeners are not correctly held by any device. The stiffeners can thus deform, and this deformation will manifest itself in the finished panel. In addition, the putting in place of the vacuum bag and the wedging means can deform the vertical portions of the stiffeners. Finally, such a method requires personnel to act above the support in order to correctly position the various elements, making the work relatively difficult for the production of panels with large dimensions.
One object of the disclosure herein is to provide a method and a device for obtaining a self-stiffened panel for which the vertical portions of the stiffeners are correctly planar, so as to optimize the quality of the panel.